Superregenerative receiver



Aug. 13, 1935. AfcLAuslNG 2,010,978

SUPERREGENERATIVE RECEIVER Filed May 27, 1951 INVENTOR ARTHUR CLAUSING TTORNEY Patented Augrl3, 1935 SUPERREGENERATIVE RECEIVER Arthur Olausing, Berlin-Grunewald, Germany,

.assignor to Siemens, & Halske Aktiengesellsehaft, Siemensstadt near,.Berlin, Germany, a

corporation of Germany Application May 27, 1931, Serial No. 540,346

' InGermany September 13, 1930 8 Claims. (01. 250

'The present invention relates to regenerative receivers, and more particularly to a variable regenerative receiver. i

In the reception of radio signalsa considerable increase in signal strength or volume is attainable, whenever recourse is had to the feed back of energy from the plate circuit to the grid circuit.

regenerative action will be most marked when the system operates just below the point of spontaneous oscillation. Indeed, the gain obtainable with a receiver working at the point just ahead of incipient self-oscillation is well nigh infinite.

Under practical conditions, however, itmay be pushed only to a certain degree, since in the neighborhood of incipient oscillation (i. e., when l .the damping of the system approaches close to zero), the system starts self-oscillating even in the presence, or on the arising, of a slight external excitation, withthe result that reception is rendered impossible. Now, in order that, on the one hand, a maximum of regeneration may be available, while, on the other hand, there may be a chance to receive at all, recourse has been had to a method which has been known aspendulous, or variable, regeneration.

'In this method'of reception regeneration is made so strong that the receiver will start oscillating spontaneously. -Iowever, by additional means the impedance in the grid, or the plate circuit, or in both, is periodically altered as soon as the incipient oscillation is suppressed again. These interruptions, or suppressions, occur periodically at a rate of frequency lying above the limit of audibility. i

For instance, it is customary in variable, or

pendulous, regeneration sets to operate at an interruption frequency of, say, between 15,000 and 20,000 cycles. The adjustment of proper impedance changes in this type of receiver is attended with rather serious'difficulties in practice, and as a result the manipulation and use of such a set is by no me'anssimple. It is particularly the operation of the audion that is disadvantageously afiected by the resistance changes.

In a variable regeneratiom'or super-regenerative receiver set according to this invention, in .50

order to suppress, or interrupt, the radio irequency oscillations, one of the oscillationcircuits is periodically detuned with the result that the oscillation is broken off. i

v The novel features which Ifbelieve to be characteristic of my invention are set forth in particularity in the appended c1aims,-the invention itself, however, as to both its organization and This insures reduction indamping of the receiver system, and thusian increased gain in the incoming radio frequency oscillations. The

indicated diagrammatically several circuit organizations whereby my invention may be carried into effect. l 1

In the drawing,

Fig. 1 shows one form of the invention,

Fig. 2 shows a modification,

Fig. 3 is a graphic representation of the modi-' fication inFig. 2.

One practical embodiment is shown in Fig. 1. The radio frequency oscillations collected by the grounded antenna circuit l are fed through the coupling coil 2 to the grid oscillation circuit comprising the inductance 3 and the variable tuning condenser 4. The grid oscillation circuit is disposed between cathode 5 and grid I of an electron discharge tube 8 in series with a grid biasing battery 5.

The anode circuit consists of the plate battery .Land a plate oscillation circuit comprising an inductance coil Wand atuning condenser H in shunt with the coil H3. The indicator instrument l2, say, a loudspeaker, is shunted by a blocking condenser l3, and is connected with the plate l4.

.By means of an auxiliary generator [5, there is controlled, forinstance, a condenser type of microphone I6 whose oscillating diaphragm ll influences the field of condenser ll thereby occasioning periodic tuning variations of the plate oscillation circuit. "These alterations in tuning must be so large that the oscillation set up under tuned condition of the grid circuit and the plate oscillation circuit will be suppressed again. 7 The generator 15 is of any well knownconstruclations due to common resonance of the gridand plate circuits are periodically suppressed whenever the plate circuit is detuneda Another practical example is illustrated in Fig. 2. The tube R has a grid oscillation circuit which consists of a piezo-electric crystal; for example, aquartz crystal Q. In the plate circuit, on the contrary, there is an oscillation circuit consisting of an inductance coil L and a variable condenser C. Plate potential is furnishedirom platebattery B being in series connection with a measuring instrument M indicating the plate direct current, the elements B and M being shunted by a condenser K. Such a scheme, as illustrated in Fig. 2, has the property of starting to oscillate whenever the oscillation circuit L, C is tuned to the natural period of thecontrol crystal Q.

The behavior of such an arrangement is shown in Fig. 3 graphically illustrating the wave length (abscissae) plotted against the plate directcurrent is. as read in the instrument M (ordinates). If the oscillation circuit L, C is not tuned to the natural period of the quartz crystal Q, then a certain constant plate direct current is present, the value of which is a function of the type of tube employed and the operating data. In the presence of a certain approximation of the tuning, the system starts oscillating, with an incidental and simultaneous decrease in the plate current. The point of incipient oscillation is marked by a in Fig. 3.

The plate direct current falls off to a certain point b. But as the wave length of the oscillation circuit L, Cis further increased, even if only by a minute amount, the oscillation is suddenly suppressed, and the plate direct current is restored'to value c, being of the same value as a. The transition from b to c is extremely critical, and manifests itself in the measuring instrument M by a sudden movement of the needle. Even extremely small changes in capacity of C sufiice to cause the system to change from the oscillating to the non-oscillating state. If, then, one proceeds inversely by changing from greater wave lengths towards shorter waves, the oscillation just as abruptly will be restored, and this becomes apparent from the fact that the plate direct current decreases from value c to value b.

This phenomenon may be used in the construction of a heterodyne receiver set. For if similarly as in the example Fig. 1 care is taken so that the tuningof the plate oscillation circuit L, C, Fig. 2 is periodically altered, then, even with minimal changes in tuning, conditions may be secured where the oscillation breaks off entirely. It is, of course, immaterial whether the tuning is altered by changing L, or changing C.

While I have indicated and described several systems for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is' by no means limited to the particular organizations shown and described, but that many modifications may be made without departing from the scope of my invention as set forth in the appended claims.

What is claimed is: 1. A super-regenerative receiver comprising a tube having a signal input circuit and a resonant output circuit, said circuits normally being resonant to the same frequency, and means for pcriodically varying the resonance frequency of the output circuit from the input circuit resonance frequency to considerably less than said latter frequency, said variation being at a super-audible rate.

2. A super-regenerative receiver comprising a tube having a signal input circuit and a resonant output circuit, said circuits normally being resonant to the same frequency, and means for pericdically varying the resonance frequency of the output circuit from the input circuit resonance frequency to considerably less than said latter frequency, said variation being at a super-audible rate, said input circuit including a piezo-electric tube having a signal input circuit and a resonant output circuit, said circuits normally being resonant to the same frequency, and means for pcriodically varying the resonance frequency of the output circuit from the input circuit resonance frequency to a value considerably less than said latter frequency, said variation being at a superaudible rate, said tube having an inherent grid to plate capacity path for the feed-back of radio frequency energy from the output to the input circuit.

4. In combination, in a super-regenerative receiver, an electron discharge tube provided with an input and output circuit, both circuits being normally resonant at a predetermined frequency, a piezo-electric device in said input circuit, and means for varying the resonance of the output circuit at a super-audible frequency.

5. In combination, in a super-regenerative receiver, an electron discharge tube provided with an input and output circuit, both circuits being resonant to the same frequency, a piezc-electric device in said input circuit, a variable condenser in said output circuit to tune the latter, and means for varying the resonance of the output circuit at a super-audible frequency.

6. In a radio receiver adapted to be connected to an antenna system an electronic tube having anode, cathode and grid electrodes, said grid being included in an input circuit of said tube and said anode in an output circuit thereof, capacity between said circuits including the natural capacity inherent between said grid and plate electrodes, said circuits being normally resonant at a predetermined frequency, means for periodically varying the resonance frequency of the output circuit up to and away f om the resonance frequency of the input circuit at a super-audible frequency whereby said tube is periodically placed in condition to oscillate.

7. In a super-regenerative receiver an electron discharge tube provided with an input circuit and an output circuit, a piece-electric crystal connected in said input circuit for making said input circuit sharply resonant to a predetermined frequency, a tunable circuit in said output circuit said tunable circuit being normally resonant at the same frequency as the input circuit to' permit said tube to oscillate and means for periodically varying the resonance characteristics of the output circuit so as to periodically dampen the tube to the extent that any oscillations generated thereby are stopped.

8. In a super-regenerative receiver an electron discharge tube provided with an input circuit and an output circuit, a piezoelectric crystal connected in said input circuit for giving to said input circuit sharp resonating characteristics at a frequency dependent upon the characteristics of the crystal, a tunable circuit in said output circuit, coupling etween said input and output circuits including the natural. capacity coupling inherent between the grid and plate electrodes of said tube, said output tunable circuit being normally tuned to a frequency related to the frequency at which the input circuit is resonant so as to permit said tube to oscillate and means for ARTHUR CLAUSING. 

